How to read the first row of an amortization schedule
A monthly payment does not all reduce the debt. Reconcile opening balance, interest, principal reduction and closing balance to understand what a repayment schedule is showing.
Amortization calculator →Follow the calculation order
The monthly model begins with unpaid principal. It calculates interest on that balance, subtracts interest from the payment to find principal reduction, and subtracts that reduction from the opening balance. Repeating the process creates the schedule. It is the remaining principal, rather than the total original purchase price, that drives the next period’s modeled interest.
Work through one row
Take an opening balance of 20,000 and a nominal annual rate of 6% calculated monthly. The monthly rate is 0.5%. If the payment for this illustration is 600, interest is 100, principal reduction is 500 and the closing balance is 19,500. With no other changes, next month’s interest is 97.50. The assumed 600 payment explains the bookkeeping; it is not presented as the payment generated by a particular contractual term.
Investigate discrepancies systematically
A lender statement may use actual-day accrual, different payment dates, charges or rounding rules. Check those assumptions before concluding that either calculation is wrong. Insurance collected alongside a loan payment also does not repay principal. Across a complete fully amortizing schedule, principal reductions should reconcile to the original loan amount, and the final payment can be smaller than the usual instalment.
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